VOLUME 33, NO. 6, JUNE, 1956
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E ~ L CLAPEYRON E (1199-1864) H. 8. VAN KLOOSTER Rensselaer Polytechnic Institute, Troy, New York
AMONG the founders of the science of thermodynamics two Frenchmen occupy a prominent place, via., Carnot and Clapeyron, both former students of the famous Ecole Polytechnique, founded in 1794. This school owes its pre-eminent position to the fact that the number of entering students is limited to 250, chosen from over 1000 applicants from the best secondary schools in France. The curriculum extends over two years after which the graduates continue their studies in their chosen special fields. Benoit Pierre amile Clapeyron, a native of Paris, was born on February 26, 1799. He entered the &ole Polytechnique in 1816, four years after Carnot. Finishing his studies in 1818, he became a mining engineering student a t the School of Mines and was graduated in 1820. The Russian government a t that time was establishing a new school for public-works instruction and had asked for French engineers as instructors. Clapeyron and his friend L a d , also a graduate of the School of Mines, were chosen and for ten years they taught pure and applied mathematics in Petrograd. The revolution of 1830 put a sudden stop to a successful career in Russia and Clapeyron returned to Paris, a t the time when George Stephenson with his locomotive "The Rocket" opened up the prospects for railroad transportation on both sides of the Atlantic. Clapey-
ron drew up the plans for the first railroad from Paris to Saint Germain and applied his talents to the design of locomotives. His later prominent role as a builder of railroads and bridges did not detract from his activities as a scientist and teacher. He was elected a member of the Academy of Sciences in 1858, occup ing the seat of another famous alumnus of the Cole Polytechnique, via, Cauchy. For over 15 years (184944) he taught the course on steam engines at the Ecole des Ponts in Paris. Early in his railroad career, when looking for a relation between power production and coal consumption, Clapeyron came across Carnot's 60-page brochure, "Reflexions sur la puissance motrice du feu," published in 1824. This was a revelation to Clapeyron and led to the publication in 1834 of his "MBmoire sur la puissance motrice de la chaleur" in which he first developed the graphical methods of cyclical processes, resulting in the well-known equation that bears his name:
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This equation was first published in the Journal de llEcole Polytechnique [IS, 170 (1834)l and later also appeared in the Annales de Physique [(2) 59, 446 (1843)l. Clapeyron died on January 28, 1864.
